This is actually the perfect example of an otherwise great plug-in slightly marred by inconsistent functionality.
NippleClippingReducer works wonders on clothes not optimally designed for physics to help you out, or for clothes without sim physics at all, but it appears to only affect a selection of possible nipple morphs and doesn't work perfectly on every clothing item.
It can also occasionally leave models with the altered nipple settings in the undressed state, depending on you remove the clothing? I can't recall the specifics on this but I've definitely encountered it.
Still, I've used it more than once in my scenes to prevent from nosy nips poking through during various activities, so give it a shot!
